1. Field of the Invention
The present invention relates to a fixing apparatus which performs a fixing treatment of a recording medium bearing an image which has not been fixed and an image forming apparatus which is equipped with the fixing apparatus.
2. Related Background Art
There is conventionally known and put to practical use a fixing apparatus 100 equipped, as shown in FIG. 11, with a fixing rotary body 102 which is in contact with a non-fixed image bearing surface of a recording medium 101, a press rotary body 103 which is in pressure contact with the fixing rotary body 102 through the recording medium 101, and a plurality of sheet discharge rotary body pairs 104 which nip, convey and discharge the recording medium 101 subjected to a fixing treatment out of a fixing apparatus main body: each of the sheet discharge rotary body pairs 104 including an upper rotary body 105 which is to be in contact with the surface of the recording medium 101 and a lower rotary body 106 which is in pressure contact with the upper rotary body 105 through the recording medium 101.
FIG. 11 is a schematic front view showing an outline of a configuration of the fixing apparatus 100.
Speaking concretely of the fixing apparatus 100, the recording medium 101 which bears a non-fixed image is subjected to the fixing treatment while passing between the fixing rotary body 102 and the press rotary body 103, and nipped and conveyed by the plurality of upper rotary bodies 105 and the lower rotary bodies 106 which are rotating in the same direction as the fixing rotary body 102 and the press rotary body 103, thereby being discharged out of the fixing apparatus main body.
Furthermore, since the upper rotary bodies 105 which are brought into contact with a developer beared by the recording medium 101 which has been subjected to the fixing treatment, a fluoroplastic is used as a surface material for the upper rotary bodies 105 to prevent the developer from adhering to surfaces of the upper rotary bodies 105.
In the recent years where the speeding up of an image forming process is progressed, a passage from a fixing nip formed between the fixing rotary body and the press rotary body to a sheet discharge nip formed between the upper rotary body and the lower rotary body tends to be shortened as a measure to speed the an image forming process.
However, the conventional fixing apparatus 100 in which rotating shafts of the upper rotary bodies 105 are in parallel with rotating shafts of the fixing rotary body 102 and the press rotary body 103 as shown in FIG. 11 can hardly prevent a semi-melted developer on the recording medium 101 having been subjected to the fixing treatment from adhering to surfaces of the upper rotary bodies 105 even if a fluoroplastic is adopted as the surface material for the upper rotary bodies 105.
In particular, there is a tendency to use developers which have low melting points as a measure to speed the image forming process and it is extremely difficult to prevent such developers having low melting points from adhering to the surfaces of the upper rotary bodies.